Treatment of coal extracts

ABSTRACT

Phenolic compositions which may be reacted with aldehyde or aldehyde donors, e.g., formaldehyde or hexamine, to form resinous or resinifiable compositions may be manufactured by reacting a solution or extract of coal with a phenol.

United States Patent [191 Robinson et al.

[ TREATMENT OF COAL EXTRACTS [75] Inventors: Joseph Gordon Robinson,

Winchcombe; William Sydney Durham Wise, Tewkesbury, both of England [73]Assignee: Coal Industry (Patents) Limited,

London, England [22] Filed: Mar. 11, 1971 [21] Appl. No.: 123,423

[30] Foreign Application Priority Data Mar. 17, 1970 Great Britain12755/70 [52] us. on. .l 260/28 51 Int. Cl. C08g 51/52 [58] Field ofSearch 260/28 [56] References Cited UNITED STATES PATENTS 3,301,8031/1967 Schick 260/28 Clem 260/28 Primary ExaminerMorris LiebmanAssistant Examiner-P. R. Michl Attorney, Agent, or Firm-Stevens, Davis,Miller &

Mosher [57] ABSTRACT Phenolic compositions which may be reacted withaldehyde or aldehyde donors, e.g., formaldehyde or hexamine, to formresinous or resinifiable compositions may be manufactured by reacting asolution or extract of coal with a phenol.

8 Claims, No Drawings TREATMENT OF COAL EXTRACTS This invention relatestothermosetting resins, and a process for the manufacture thereof.

According to the invention a process for the manufacture of a phenoliccomposition comprises reacting a solution or extract of coal with aphenol.

The product of such a reaction is a compound of the general formulaR-(OI-l), wherein R is the residue of a solution or extract of coal, 4)is the residue of a phenol of formula OH and includes an aromatic ringand n is an integer. It is to be understood that the residue of thesolution or extract of coal may have any number of groups OH attachedthereto. A normal number will be one, two or three and certain of thegeneral formulae in this specification, by way of illustration, showcompounds where n 2.

By solution or extract of coal it is meant to include those productsformed by the treatment of coals with solvents, particularly thosesolvents that react with the coal, cleaving the molecular chainsthereof, to form a product having a mean molecular weight of less than2,000 andpreferably between 500 and 200. High boiling aromatic solventsmay be used, but it is pfeferred that the solvent should contain atleast a portion of a compound reacting with and tending to degrade thecoal, for example a compound having nitrogen as the heteroatom in a fiveor six membered heterocycle ring. Other such compounds are included inthose aromatic compounds derived from aromatic compounds having at leasttwo aromatic rings by the partial hydrogenation thereof. Additionally,or alternatively, the solution or extract of coal may be formed by thetreatment of the coal with the solvent in the presence of hydrogen. Thisdegrades the coal, diminishing the molecular weight thereof. Suitablesolvents that may be employed include oils and tars formed by thedistillation of pitches and tars, for example creosote oil and other taroils, and include also tar bases and hydrogenated tar bases. Examples ofcompounds that may be employed to form the solution or extract of coalsuitable for use in the present invention includes the following,although it will be understood that, for economic reasons, pure solventswill not normally be employed: 1,2,13,4- tetrahydroquinoline, indolene,indole, pyridine, piperidine, perhydropyrene, perhydrophenanthrene,pyrrole, 9,10-dihydroanthracene, tetralin, pyrrolidone, pyrazine,pyrene, phenanthrene, 2 -pyrrolidone, acenaphthene, anthracene,diphenylene oxide, nicotinic acid, chrysene, fluorene, fluoroanthrene,phthalic acid.

The term solution or extract of coal is not intended to be limited toproducts formed by the liquid phase dissolution or extraction of coalbut to include those products formed by treating coal, or a solution orextract thereof, with a solvent in the gaseous phase, at either above orbelow the critical pressure and temperature of the gaseous solvent, andcondensing the portion of the coal dissolved or entrained in the gaseoussolvent. Such solvents are not limited to those that are liquid atambient conditions but may include, for example, methane and othergases. Other solvents that are particularly suitable for treating thecoal in the gaseous phase include pyridine, toluene, and mixtures ofsuch solvents.

Any coal may be, in principle, employed to form the solution or extractof coal. It is, however, known that coals having a high carbon content,for example about 90 percent, are difficult to dissolve or extract,unless hydrogen is employed in large quantities. Accordingly it ispreferred to employ a coal other than that of National Coal Board CoalRank Code 100 series. Desirably the coal has a carbon content of betweenand percent and preferably between 82 and 86 percent. The term coal asused herein is intended to include materials that are of coal-likenature and which contain dissolvable material, for example lignite.Percentages of the carbon in the coal are expressed on a drymineral-matter free basis by weight.

The coal may be dissolved or extracted by a liquid at an elevatedtemperature, desirably between 300 and 450 C. The prefered temperatureis about 400 C. Normal chemical engineering considerations would beapplicable to this dissolution or extraction. For example, the higherthe temperature, the more rapidly the dissolution or extraction takesplace, but the more undesirable by-products, particularly cokes, areformed. The dissolution or extraction can take place in any suitablemanner. One method, if the dissolution or the extraction is by a liquid,is by digestion of the coal with the solvent, the solvent being inexcess, at an elevated temperature and then removing the solid materialthat is not dissolved from the solution, if such solid material is notrequired in the product. An alternative method is by extraction, as, forexample, in a Soxalet type of apparatus. Excess, or all, the solvent canthen be removed, for example by distillation. Any phenol may be employedin the present invention. The most convenient phenols are monocyclicmonophenols, for example phenol. Other phenols may, however, beemployed, for example the cresols, resorcinol, and the xylenols.

According to a modification of the present invention, for at least aportion of the phenol, an aromatic amine may be substituted, for exampleaniline, but other aromatic amines, including N-alkyl aromatic aminescan be employed, for example N-methylaniline and N,N- dimethylaniline.

Preferably the solution or extract of coal is reacted with the phenol ina molecular ratio of coal extract to the phenol of one to at least l.5.Advantageously, the ratio of the solution or extract of coal to thephenol may be even lower, for example between 1 to 2 and l to 3. Thegreater the amount of the phenol present, the greater the amount ofcross-linking in the cross-linked therrnoset polymer after reaction withthe aldehyde.

The reaction of the phenol with the solution or extract of the coal isadvantageously carried out in the presence of a strong acid catalyst,which may be an inerganic protonic acid, for example sulphuric acid, ora Lewis acid, for example aluminium chloride or ferric chloride.

The reaction of the phenol with the solution or extract of coal ispreferably performed at an elevated temperature, for example about 50 C.The reaction is preferably carried out in an inert atmosphere.

The phenolic composition may be reacted with an aldehyde, in any manneranalogous to those employed for previously known compounds having atleast one phenolic hydroxyl group on each of two unfused aromatic rings.Desirably the aldehyde is an aldehyde having not more than four carbonatoms. Preferably the aldehyde is formaldehyde. An aldehyde donorforming the aldehyde under the reaction conditions or otherwise reactingto introduce the equivalent to an aldehyde residue may be employed, forexample hexamine or paraldehyde.

The aldehyde may be reacted with the phenolic composition at arelatively low temperature, for example below about 100 C, in alkalineconditions to form a resol. Such a resol formed by the reaction offormaldehyde may be represented as having the general formula:

wherein m is an integer which may differ at each of its occurrences inany molecule. Depending on the relative amount of formaldehyde employed,the number of methylol groups present may vary. Such resols may bedissolved in an organic solvent to form a varnish.

If the aldehyde is reacted with the product of the reaction of thephenol with the solution or extract of coal in acidic conditions, athermoplastic polymer or novolak is formed. This is a substantiallylinear polymer having, in the case where the aldehyde is formaldehyde,as chain extending groups, and preferably as substantially the onlychain extending groups, groups have the general formulae If the aldehydeis reacted with the product of the reaction of the phenol with thesolution or extract of coal at a relatively higher temperature, forexample above about 100 C, in alkaline conditions, or the resol istreated with an acid, or the thermoplastic product or novolak is reactedwith an aldehyde in the presence of a base, the product will normally becross-linked thermosetting polymer. The reaction at the relativelyhigher temperature may be considered as equivalent to carrying out thereaction of the resol with the acid or the thermoplastic product ornovolak with the aldehyde in the presence of the base concurrently withthe formation of the resol or the thermoplastic produce or novolak. Sucha cross-linked, thermoset polymer, formed by the reaction offormaldehyde, may be represented generally as having the followinggeneral formula, indefinitely extended:

Depending on the relative amount of formaldehyde employed, there may bemore or fewer methylene bridges and/or methylol groups and/oroxydime'thylene (CH .O.CH bridges. Depending on the amount of phenolemployed, there may be more or less crosslinking.

The products may be modified in analogous way to those resins derivedfrom phenols having one phenolic hydroxyl group on each of two non-fusedaromatic rings. The resols or the product of the reaction of the phenolwith the solution or extract of coal may be mixed with other phenoliccompounds, or other compounds which react with system. Lubricants and/orfillers may be added to vary the characteristics of the products.

The products exhibit good thermal stability and good mechanical andelectrical properties combined with low moisture absorption.

The invention is illustrated by the following examples in which allparts are parts by weight.

Preparation of a Solution or Extract of coal 1 part of Markham coal, ofNational Coal Board coal rank code 802, was treated with 3 parts of amixture of tetrahydronaphthalene and l-methylnaphthalene in a ratio of 1to 1 at 400 C for 1 hour at autogenicpressure and was then filtered togive a solution or extract of coal containing percent by weight of thecoal, having a mean molecular weight of about 750, and having asoftening point of between and 180 C. The solution or extract of coal soprepared was used in the following examples.

Example 1 One part of the solution or extract of coal, two parts ofphenol and 0.4 parts of p-toluene sulphonic acid were heated togetherunder nitrogen at 180 C for 24 hours. The product was then cooled andpulverised. The powder produced was washed with boiling water until nomore phenols or other acidic compounds were washed out. The product wasdried at 60C under reduced pressure. This product was mixed with 0.2parts of hexamine and compression moulded at 160 C under a pressure of7MN/m to form a hardened, infusable, insoluble resin.

Example 2 One part of the solution or extract of coal, two parts ofphenol and 0.4 parts of anhydrous ferric chloride were heated togetherat 180 C under notrogen for 24 hours with stirring. The product wascooled, pulverised and washed with boiling water until phenols and otheracidic compounds could no longer be washed out. The product was thendried at 60 C under reduced pressure.

The resin was blended with 0.2 parts of hexamine and compression mouldedat 160 C under a pressure of 7MN/m to form a hardened infusable,insoluble resin.

Example 3 One part of the solution or extract of coal, two parts ofphenol and 0.4 parts of p-toluene sulphonic acid were heated togetherunder nitrogen at 180 C for 24 hours. The cooled and pulverised productwas washed with boiling water to remove unreacted phenol and the acidcatalyst. The product was dried at 60 C under reduced pressure. Theproduce was then mixed with 1% parts of cotton linters, 0.1 partsmagnesium oxide 0.5

parts calcium stearate, 5 parts of a phenolic novolak, 0.4 parts phenoland 3 parts of hexamine. This mixture was blended on a two-roll mill andtransfer moulded at 160 C under a pressure of 7MN/m to give an infusibleand insoluble artefact of tensile strength l4MN/m Such cross-linkedthermoset polymers include groups of the general formula:

l R "Taod li.

We claim:

1. in a process for the production of a resinous or resinifiablecomposition by the reaction of a phenolic compound having at least onephenolic hydroxyl group on each of two unfused aromatic rings with analdehyde having not more than four carbon atoms, or an aidehyde donorforming the aldehyde having not more than four carbon atoms under thereaction conditions or otherwise reacting with the phenolic compound tointroduce the equivalent to a residue of the aldehyde, said reactionbeing carried out under alkaline conditions, the improvement whichcomprises employing as at least part of the phenolic compound a phenoliccomposition formed by reaction a solution or extract of coal with aphenol selected from the group consisting of monocyclic monophenols andresorcinol, said phenolic composition consisting of compounds of the general formula 6 i wherein R is the residue of the solution or extract ofcoal, and d) is the residue of said phenol, said phenol having a formulaOH and n is an integer, said solution or extract of coal including thoseproducts formed by the treatment of coal with a solvent, said solventbeing, during said treatment, in either a liquid or a gaseous phase,said treatment being carried out in the presence of an inert gas orhydrogen. said treatment being carried out at an elevated temperaturewhereby molecular chains of the coal are cleaved in saidtreatrncnt.

2. A process as claimed in claim 1 wherein said solvent includes one ormore compounds selected from heterocyclic compounds having a nitrogenatom as the hetero-atom in a 5 or 6 membered ring and heterocyclic orhomocyclic compounds having at least one aromatic ring derived fromaromatic compounds having at least two aromatic rings by the partialhydrogenation thereof.

3. A process as claimed in claim 2 wherein said phenol is phenol andsaid residue 42 is a phenylene radical.

4. A process as claimed in claim 3 wherein at least a portion of thealdehyde is formaldehyde.

5. A process as claimed in claim 3 wherein at least a portion of thealdehyde donor is hexamine.

6. A resinous or resinifiable product of claim 1.

7 The resinous or resinifiable product of claim 4.

8. The resinous or resinifiable product of claim 5

2. A process as claimed in claim 1 wherein said solvent includes one ormore compounds selected from heterocyclic compounds having a nitrogenatom as the hetero-atom in a 5 or 6 membered ring and heterocyclic orhomocyclic compounds having at least one aromatic ring derived fromaromatic compounds having at least two aromatic rings by the partialhydrogenation thereof.
 3. A process as claimed in claim 2 wherein saidphenol is phenol and said residue phi is a phenylene radical.
 4. Aprocess as claimed in claim 3 wherein at least a portion of the aldehydeis formaldehyde.
 5. A process as claimed in claim 3 wherein at least aportion of the aldehyde donoR is hexamine.
 6. A resinous or resinifiableproduct of claim
 1. 7 The resinous or resinifiable product of claim 4.8. The resinous or resinifiable product of claim 5.